thanks for your question. This is possible with some CSS code. Please try adding

.tablepress tbody td {
background-color: #ff0000;
}

to the "Custom CSS" textarea on the "Plugin Options" screen of TablePress.
This will change the background color of all tables.
For more examples, please see the plugin FAQ page at http://tablepress.org/faq/

thanks for the link.
You'll just have to uncheck the "Alternating row colors" checkbox on the table's "Edit" screen, and the color change will work as expected.
Then just change the color value to what you want.